Dual-mode sideband interface for smart network interface controller

1. An information handling system comprising:

a host system including a first root complex;

a management controller including a second root complex;

a network interface controller; and

at least one switching circuit;

wherein the information handling system is configured to, in response to the host system being powered on:

couple the network interface controller to the management controller via the first root complex; and

wherein the information handling system is further configured to, in response to the host system being powered off:

activate the at least one switching circuit to couple the network interface controller to the management controller via the second root complex.

2. The information handling system of claim 1 , wherein the network interface controller comprises a plurality of network interface controllers.

3. The information handling system of claim 1 , wherein the network interface controller comprises a SmartNIC.

4. The information handling system of claim 1 , wherein the first and second root complexes comprise Peripheral Component Interconnect Express (PCIe) root complexes.

5. The information handling system of claim 4 , wherein the at least one switching circuit comprises a PCIe switch.

6. The information handling system of claim 1 , wherein the at least one switching circuit comprises a multiplexer.

7. A method comprising:

while a host system that includes a first root complex is powered on, coupling a network interface controller to a management controller via the first root complex, wherein the management controller includes a second root complex; and

in response to the host system being powered off, activate at least one switching circuit to couple the network interface controller to the management controller via the second root complex.

8. The method of claim 7 , wherein the network interface controller comprises a plurality of network interface controllers.

9. The method of claim 7 , wherein the network interface controller comprises a SmartNIC.

10. The method of claim 7 , wherein the first and second root complexes comprise Peripheral Component Interconnect Express (PCIe) root complexes.

11. The method of claim 10 , wherein the at least one switching circuit comprises a PCIe switch.

12. The method of claim 7 , wherein the at least one switching circuit comprises a multiplexer.

13. An article of manufacture comprising a non-transitory, computer-readable medium having instructions thereon that are executable by a processor of an information handling system for:

while a host system that includes a first root complex is powered on, coupling a network interface controller to a management controller via the first root complex, wherein the management controller includes a second root complex; and

in response to the host system being powered off, activate at least one switching circuit to couple the network interface controller to the management controller via the second root complex.

14. The article of claim 13 , wherein the network interface controller comprises a plurality of network interface controllers.

15. The article of claim 13 , wherein the network interface controller comprises a SmartNIC.

16. The article of claim 13 , wherein the first and second root complexes comprise Peripheral Component Interconnect Express (PCIe) root complexes.

17. The article of claim 16 , wherein the at least one switching circuit comprises a PCIe switch.

18. The article of claim 13 , wherein the at least one switching circuit comprises a multiplexer.